Hitherto, however, it has not been found possible to free the materials employed completely from phosphorus compounds which yield phosphates by enzymic hydrolysis during the experiment, but it has been found that when the phosphate contents are reduced to as low a limit as possible, the amount of sugar fermented becomes correspondingly small, and, further, that in these circumstances the addition of a small amount of phosphate or hexosephosphate produces a relatively large increase in the fermenting power of the enzyme. When the total phosphorus present is thus largely reduced, the increase produced by the addition of a small amount of phosphate may amount to as much as eighty-eight times the original, in addition to the quantity equivalent to the phosphate, whilst the actual total evolved, including this equivalent, may be as much as twenty times the original fermentation. This result must be regarded as strong evidence in favour of the view that phosphates are indispensable for alcoholic fermentation. The results indicated above were experimentally obtained in three different ways and are exhibited in the following table. In the first place (cols. 3 and 4), advantage was taken of the fact that the residues obtained by filtering yeast-juice through a Martin gelatin filter (p. 59) are sometimes found to be almost free from mineral phosphates, whilst they still contain a small amount of co-enzyme. The experiment then consists in comparing the fermentation produced by such a residue poor in phosphate with that observed when a small amount of phosphate is added. The second method (col. 5) consisted in carrying out two parallel fermentations by means of a residue rendered inactive by filtration [p056] and a solution of co-enzyme free from phosphate and hexosephosphate (p. 67) [Harden and Young, 1910, 2]. The third method (col. 6) consisted in washing zymin with water, to remove soluble phosphates, and then adding to it a solution of co-enzyme containing only a small amount of phosphate, and ascertaining the effect of the addition of a small known amount of hexosephosphate upon the fermentation produced by this mixture [Harden and Young, 1911, 1].